A Ceph storage cluster is created on top of the commodity hardware. This commodity hardware includes industry-standard servers loaded with physical disk drives that provide storage capacity and some standard networking infrastructure. These servers run standard Linux distributions and Ceph software on top of them. The following diagram helps you understand the basic view of a Ceph cluster:
As explained earlier, Ceph does not have a very specific hardware requirement. For the purpose of testing and learning, we can deploy a Ceph cluster on top of virtual machines. In this section and in the later chapters of this book, we will be working on a Ceph cluster that is built on top of virtual machines. It's very convenient to use a virtual environment to test Ceph, as it's fairly easy to set up and can be destroyed and recreated anytime. It's good to know that a virtual infrastructure for the Ceph cluster should not be used for a production environment, and you might face serious problems with this.